Attachments to drive belts, particularly toothed drive belts, or chains are typically at only a single point and generally the exact position of the attachment is not critical for conveying or transport applications. Attachments may be made through protrusions extruded into or bonded to the back of the toothed belt or screwed or rivetted through the belt from the tooth side. In some examples the attachment is concealed within the tooth, such as disclosed in EP1092657A where a captive insert is buried in the tooth, or within the root of the tooth gap, such as disclosed in JP2005-075488A. In others it protrudes from the tooth side and requires modification of mating pulleys, to avoid the attachment, such as disclosed in JP2000-095316A. A disadvantage of a single attachment point is that it relies on belt tension to make it stable. Any loading on protruding attachments will tend to flex the belt easily.
DE102004032735A discloses a toothed belt having attachments each connected to the belt at two points. The stability of the attachment is improved over those having a single attachment point but the attachment points are too close to provide a precise position when the attachment is loaded.
EP1245510A discloses a device that attaches to a toothed belt at two points. Due to the width of the device, it is necessary that the device bends the belt so that can more easily ride around the cog rollers. However, in time, this will lead to localised stretching of the belt and inaccurate positioning.
A transfer system is required in which a payload is loaded onto an attachment of a belt, or the like, while positioned on a pulley. Existing systems will not provide sufficiently accurate and repeatable positioning. This is particularly evident where the loading involves exerting force on the transfer system to lock the payload onto it.
There is therefore a need in the art for an improved attachment for securing onto a belt or chain that is more stable when secured and can be used to provide accurate and repeatable positioning.